Subject: Re: Possible double-free in the usbnet driver

From: Oliver Neukum <[email-masked]>
Date: Sat, 05 Mar 2016 16:51:30 +0100

On Fri, 2016-03-04 at 14:43 -0800, Linus Torvalds wrote:

> So you have usbnet_defer_kevent() getting triggered, which in turn
> ends up using "usbnet->kevent"
> 
> But somebody like Oliver is really the right person to check this. For
> example, it's entirely possible that we should just instead do
> 
>         cancel_work_sync(&dev->kevent);
> 
> before the "free_netdev(net)" in the "out1" label.

Hi Bjorn,

I thinbk Linus has analyzed this correctly, but the fix really needs
to cancel the work, because we can also fail later after bind() has
already run. However, still cdc-ncm and the other drivers should clean
up after themselves if bind() fails, as usbnet really cannot known what
the subdrivers have done.

So in conclusion, I think Linus' fix should also go into cdc-ncm.

	Regards
		Oliver